Eberhard Pulz

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A Quasi Absolute Optically Pumped Magnetometer
for the Permanent Recording

• Eberhard Pulz
• Karl-Heinz Jäckel, Oliver Bronkalla

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• Introduction
• Sersons Method
• Measuring Method
• Cs-He-Magnetometer
• Coil System and Switching Technique
• Theoretical Estimations and Limits
• Results
• Coils Orientation
• Conclusion

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Sersons Method
T - A
T
A
F_
S
F
0
F
A - additional field strength Fo - magnetic
field strength without an additional field F/-
magnetic field strength with an additional
field S auxiliary quantity T magnetic
field strength at desired direction

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Measuring Sequence for Each Second
180 msec
C
E-
F
C
E-
time msec
0 200 400 600 800 1000
frequency counter in operation 180 msec current
switching
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Cs-He-Magnetometer
Cs-He- Sensor
Cs - Lamp
Cs- Sensor
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He Conversations Formula
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Measurement Arrangement
Magnetometer Electronics
Sensor Coils
GPS 10Mz Clock
Frequency Counter
Switching Unit
Current Supple
LINUX Computer
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Estimation of Errors

• Additional field strength
• for a given magnetometer noise about 0,005nT rms
  and a desired noise in the components of 0,01nT
  rms/sec
• additional field strength of about 5000nT
• Effect of tilting of the vertical axis of the
  bias coil
• for 1tilting, we got for ?H 13nT
• Effect of tilting the azimuth angle between the
  additional
• Field and the magnetic meridian
• for 1tilting, we got for ?H 1-10-3nT

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D
D
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Conclusions

• Cs-He magnetometer absolute accuracy lt 0.1
  nTsum of noise at NGK lt 5 pT rms _at_ 180 msec
• Orthogonal coil systemsuspendedturnable (in
  work)LASER controlled
• Realtime (GPS) LINUX-controlled system
• Result 1 sec mean values for all components
• Reducing the number of manually absolute
  measurements to some / year
• Thank you for your attention